1. Field of the Invention
The present invention relates to a light-emitting diode with high lighting efficiency and a fabrication thereof.
2. Description of the Prior Art
Nowadays, light-emitting diodes, have been used in a wide variety of applications, e.g., key systems, back light modules of mobile phone monitors, illuminating systems of vehicles, decorative lamps, and remote controls. To ensure high functional reliability as great as possible and a low power requirement of the light-emitting diodes, the lighting efficiency is required for the devices.
Please refer to FIG. 1. FIG. 1 illustrates a light-emitting diode 1 in the prior art. As shown in FIG. 1, the light-emitting diode 1 includes a substrate 10, an N-type GaN layer 11, a light-emitting layer 12, a P-type GaN layer 13, and two electrodes 14, 15. For the work of the light-emitting diode 1, the N-type GaN layer 11 and the P-type GaN layer 13 must be electrically conducted with each other, which is realized by the electrode 15 formed on the P-type GaN layer 13 and the electrode 14 formed on the N-type GaN layer 11.
In principle, the lighting efficiency of a light-emitting diode is determined both by the internal quantum efficiency and light-extraction efficiency. The internal quantum efficiency is determined by the material property and quality. The light-extraction efficiency refers to the proportion of radiation emitted from the interior of the device the device into surrounding air or encapsulating epoxy. Although many light-emitting diodes with various structures have been presented, how to enhance the lighting efficiency and the light-extraction efficiency of light-emitting diodes is still an significant issue.